forked from MetaCubeX/gvisor
-
Notifications
You must be signed in to change notification settings - Fork 0
/
mqfs.go
109 lines (93 loc) · 3.59 KB
/
mqfs.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
// Copyright 2021 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package mqfs provides a filesystem implementation to back POSIX message
// queues.
package mqfs
import (
"fmt"
"github.com/MerlinKodo/gvisor/pkg/context"
"github.com/MerlinKodo/gvisor/pkg/sentry/fsimpl/kernfs"
"github.com/MerlinKodo/gvisor/pkg/sentry/kernel/auth"
"github.com/MerlinKodo/gvisor/pkg/sentry/kernel/ipc"
"github.com/MerlinKodo/gvisor/pkg/sentry/kernel/mq"
"github.com/MerlinKodo/gvisor/pkg/sentry/vfs"
)
const (
// Name is the user-visible filesystem name.
Name = "mqueue"
)
// FilesystemType implements vfs.FilesystemType.
//
// +stateify savable
type FilesystemType struct{}
// Name implements vfs.FilesystemType.Name.
func (FilesystemType) Name() string {
return Name
}
// Release implements vfs.FilesystemType.Release.
func (FilesystemType) Release(ctx context.Context) {}
// GetFilesystem implements vfs.FilesystemType.GetFilesystem.
func (ft FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) {
// mqfs is initialized only once per ipc namespace. Each ipc namespace has
// a POSIX message registry with a root dentry, filesystem, and a
// disconnected mount. We want the fs to be consistent for all processes in
// the same ipc namespace, so instead of creating a new fs and root dentry,
// we retreive them using IPCNamespace.PosixQueues and use them.
i := ipcNamespaceFromContext(ctx)
if i == nil {
return nil, nil, fmt.Errorf("mqfs.FilesystemType.GetFilesystem: ipc namespace doesn't exist")
}
defer i.DecRef(ctx)
registry := i.PosixQueues()
if registry == nil {
return nil, nil, fmt.Errorf("mqfs.FilesystemType.GetFilesystem: ipc namespace doesn't have a POSIX registry")
}
impl := registry.Impl().(*RegistryImpl)
impl.fs.VFSFilesystem().IncRef()
impl.root.IncRef()
return impl.fs.VFSFilesystem(), impl.root.VFSDentry(), nil
}
// filesystem implements kernfs.Filesystem.
//
// +stateify savable
type filesystem struct {
kernfs.Filesystem
devMinor uint32
}
// Release implements vfs.FilesystemImpl.Release.
func (fs *filesystem) Release(ctx context.Context) {
fs.Filesystem.VFSFilesystem().VirtualFilesystem().PutAnonBlockDevMinor(fs.devMinor)
fs.Filesystem.Release(ctx)
}
// MountOptions implements vfs.FilesystemImpl.MountOptions.
func (fs *filesystem) MountOptions() string {
return ""
}
// ipcNamespace defines functions we need from kernel.IPCNamespace. We redefine
// ipcNamespace along with ipcNamespaceFromContext to avoid circular dependency
// with package sentry/kernel.
type ipcNamespace interface {
// PosixQueues returns a POSIX message queue registry.
PosixQueues() *mq.Registry
// DecRef decrements ipcNamespace's number of references.
DecRef(ctx context.Context)
}
// ipcNamespaceFromContext returns the IPC namespace in which ctx is executing.
// Copied from package sentry/kernel.
func ipcNamespaceFromContext(ctx context.Context) ipcNamespace {
if v := ctx.Value(ipc.CtxIPCNamespace); v != nil {
return v.(ipcNamespace)
}
return nil
}